1. Field of the Invention
The present invention generally relates to a fuse box device including a fuse unit and a fuse box housing the latter. Such a fuse box device can usually be fitted directly to a battery mounted in automobiles.
2. Description of Background Information
An example of a known fuse box device is shown in FIG. 1. In this figure, the fuse box device 61 includes a fuse box 62, in which a plurality of flat fuses 63 are provided. The flat fuses 63 are formed of an electrically conductive metal plate, and each fuse includes a fuse element portion 64 interposed between two ear portions with a respective ear hole for bolting 65. The fuse box 62 is manufactured by molding a resin. The fuse box has a cavity 66 capable of containing a plurality of flat fuses 63. The base of the cavity 66 is provided with one or several flat input nuts 67 and flat output nuts 68. Both flat nuts 67 and 68 are insert-molded. The flat input nut 67 is fixed to a terminal which is directly attached to a battery (not shown in the figures). To this end, the flat input nut 67 has a nut hole for bolting. When a flat fuse 63 is mounted in the fuse box 62 and the nut hole is fitted with a bolt 69, a first end portion of the flat fuse 63 is connected and fixed to the flat input nut 67. Likewise, the flat output nut 68 has a nut hole for bolting. A second end portion of the flat fuse 63 is connected and fixed to the flat output nut 68 through a bolt 69 in the same manner.
In a wire harness 70 containing several electrical cables 71, each electrical cable 71 is fitted with an LA terminal 72 (or a ring terminal). The LA terminal 72 can thus be connected and fixed to the flat output nut 68 through the bolt 69, together with the flat fuse 63. Further, the fuse box 62 is protected by a fuse cover 73.
In the prior art, the flat fuses 63 and the terminal directly connectable to a battery were prepared separately, and fixedly connected to each other through flat input nuts 67 and bolts 69. Likewise, the flat fuses 63 and the LA terminals 72 were prepared separately, and connected to each other through flat output nuts 68 and bolts 69. Such a fixing mechanism necessarily increases the number of component parts used and, consequently, production costs.
In addition, such a process, carried out during manufacture, tends to cause spurious fixing, e.g., skewed fixing, or fixing was simply omitted fixing in some cases. To avoid such situations, a high level of process control has to be implemented.
In general, the size of flat input nuts 67 and flat output nuts 68 determines the total size of a fuse box device 61. However, there is a certain limit to miniaturizing of such flat nuts 67 and 68. Moreover, when a flat fuse 63 is to receive a large electric current, sufficiently large flat nuts 67 and 68 must be used in order to reduce electrical resistance. This in turn makes miniaturization more difficult.
The present invention has been contemplated in view of solving such problems. The fuse box device according to the present invention needs only a limited number of component parts and is better adapted to miniaturization than the conventional devices. Its construction is conceived such as to reduce fixing errors and can be implemented at lower costs.
To this end, there is provided a fuse box device including a fuse unit and a fuse box, the fuse unit including at least one fuse element portion having a first end portion and a second end portion. The first end portion is formed unitarily and in one piece with an input terminal directly connectable to a battery, while the second end portion is formed unitarily and in one piece with at least one output terminal connectable to a wire harness. The fuse unit is then contained in the fuse box such that only part or the entirety of the input terminal is positioned outside the fuse box.
Preferably, the fuse unit includes an insulator-molded portion covering at least a portion of the fuse element portions.
Preferably yet, the at least one output terminal includes a plurality of output terminals and the fuse box contains at least one insulator partition wall such as to define a plurality of enclosures, so that each enclosure contains an output terminal connectable to a press-fit terminal of one of the electrical cables which constitute a wire harness.
Suitably, the fuse box includes at least one holder for defining a fixing position for the fuse unit and fixing the latter in the fuse box by holding part of the fuse unit by the holder.
Typically, the fuse box includes two opposing inner faces, the insulator partition walls have a top portion, and the fuse box device further includes a cover joint having an inner face. The at least one holder is then selected from the group consisting of: at least one slit formed in the insulator partition walls so as to extend from the top portion thereof to a half-way point downward; two pairs of ribs formed in the opposing inner faces of the fuse box at positions corresponding to those of the slits; and two pairs of ribs formed in the inner face of the cover joint at positions corresponding to those of the slits.
In the above construction, the part of the fuse unit may include the insulator-molded portion.
According to a first aspect of the invention, an end portion of a fuse element portion is formed unitarily and in one piece with a terminal that is directly connectable to a battery. Accordingly, previously used fixing elements such as nuts and bolts can be eliminated. Further, the other end portion of the fuse element portion is formed unitarily and in one piece with a male tab that is connectable to a wire harness. Consequently, the fuse element portion and the wire harness can be easily connected without using any fixing elements. The number of parts used is thus reduced, and manufacturing costs are also lowered to a minimum. Besides, as the fixing elements are eliminated, spurious fitting during manufacture can be avoided, and the fuse box device as a whole can be miniaturized.
According to a second aspect of the invention, part of the fuse element portion is sandwiched by the holder, so that the fuse element portion is placed at a given position in the fuse box, and mounted therein. Accordingly, it is no longer needed to use the conventional means for fixing the fuse element portion in the fuse box. This feature also contributes to the reduction of parts number, costs and size.
According to a third aspect of the invention, upon mounting the fuse element portion into the fuse box, each male tab is inserted into a press-fitting terminal, through which the male tab is electrically connected to a wire harness. As a result, it is no longer necessary to use LA terminals and related fixing elements for binding the male tabs and the wire harness. Moreover, the press-fit terminals are separated from each other by an insulator wall, so that a short circuit between the press-fit terminals can be avoided. Furthermore, both the male tabs and the press-fit terminals are securely contained in a fuse box, so that they are better protected from external influences such as water contact.
According to a fourth aspect of the invention, the conductive fuse element portion is protected by molded resin. This molded resin makes the fuse element portion less susceptible to strain, and the fuse element portion procures a higher mechanical strength. At the same time, the molded resin improves the insulating and waterproof quality of the fuse box.